In order to reduce emissions of CO2 of human origin into the atmosphere, processes for capturing the CO2 generated in a given process have been developed. It is a question of extracting the CO2 from a gas generated by the process, optionally purifying it and finally, in general, compressing it in order to transport it in a pipeline.
One of the routes for treating CO2 consists in distilling the CO2-rich gas stream in a cryogenic purification unit.
In such a unit, it is necessary to compress the incoming gas: it being possible for the incoming gas to be flue gases resulting from a process such as an adsorption purification process or a blast furnace process.
For applications that treat wet CO2, that is to say comprising at least 0.1% water, the use of stainless steel compressors is recommended since the condensation of the wet CO2 forms carbonic acid which is highly corrosive for carbon steels. However, the use of stainless steel compressors leads to a plant that has a high cost.
Furthermore, document FR-A-1412608 teaches a plant for intermediate cooling of compressed gas comprising compressors associated with exchangers and a cooling water circuit. The consecutive exchangers are connected in series to the cooling water circuit. Similar teaching is given by documents WO-A-2011/088527, US-A-2011/000227 and U.S. Pat. No. 7,269,956.